The present invention relates to a candle, which expression herein refers to all forms of lighting and/or heating devices in which absorbent wick means are supported in a body of fuel, the wick means and the body of fuel have corresponding top and base regions, whereby in use the top region of the body of fuel falls as the fuel is consumed and a top portion of the wick means projects from the top region of the body of fuel to serve as a combustion station at which fuel conveyed by the wick means from the body of fuel is combusted to create a flame for lighting and/or heating. The fuel is typically solid at room temperature, but melts in the vicinity of the flame. The projecting top portion of the wick is itself combusted by the flame and thereby maintains a projecting length, which is typically approximately constant, serving as the combustion station as the body of fuel is consumed.
Wax candles have been known for many centuries. In recent times, air modifying agents such as fragrances have been incorporated into the fuel, with the result that the agent is released into the atmosphere when the candle is used. Still further, in recent times the traditional wax fuels have been replaced in some cases by oil-based fuels, which typically contain an amount of a combustible polymer such as a triblock copolymer (e.g. KRATON (TM)) to solidify the hydrocarbon oil at room temperature.
It has long been known to bound the base region of the body of fuel by an enclosure (xe2x80x9ccandle holderxe2x80x9d) during use, to restrict dripping of the molten fuel. However, it has also become common in recent times for at least the base region of the body of fuel to be permanently bounded by an enclosure, with the additional purpose of simplifying the manufacturing process. The enclosure suitably comprises a base wall and optionally a side wall. The enclosure may, for example, be of metal or glass. During manufacture, the base end of the wick is anchored to the central region of the base wall and the wick is held taut. The fuel is then introduced around the wick in heated, liquid, form and allowed to solidify by cooling.
Such known devices suffer from the general disadvantage that their low-burning performance is rather poor. Typically, a certain amount of the fuel may be left unconsumed after the wick has been combusted. Moreover, in some cases there can be a risk of metal parts of the enclosure overheating as the flame burns low, which can potentially lead to uncontrolled flash ignition of the fuel and/or heat damage to the enclosure or any structure on which the arrangement is standing.
The present invention aims to go at least some way towards overcoming the above disadvantages to provide an improved or at least alternative low-burning candle.
According to the present invention, therefore, there is provided a candle comprising:
a body of fuel having top and base regions thereof;
absorbent wick means supported within the body of fuel and having top and base regions corresponding to the top and base regions or the body of fuel, whereby in use the top region of the body of fuel falls as the fuel is consumed and a top portion of the wick means projects from the top region of the body of fuel to serve as a combustion station at which fuel conveyed by the wick means from the body of fuel is combusted to create a flame; and
a spacing member comprising a first portion which substantially encircles the wick means at a location within the body of fuel above the base regions of the wick means and the body of fuel to define a lower limit of travel of the combustion station as the body of fuel is consumed and a second portion which extends below the first portion whereby the said lower limit of the combustion station is spaced above the base region of the body of fuel.
The spacing member may be thermoinsulative or thermoconductive. When relatively thermoinsulative, it may conveniently be made from glass and will function to stop the travel of the flame at a distance above the base region of the body of fuel. In due course the flame will die as the heat of the flame cannot be used to maintain the fuel in a melted condition. However, in practice it is found that the heat of the flame is sufficient to melt the fuel to a depth of about 1 cm below the flame and this molten fuel is available for combustion. When eventually the flame dies, this prevents the heat of the flame acting upon any enclosure present around the body of fuel or upon any structure on which the candle is standing. Between the time of the flame reaching its lower limit of travel and its dying, the solid fuel underlying any molten fuel near the flame acts as a heat sink and thus helps to keep the base region of the body of fuel and any surrounding enclosure cooler than would be the case with conventional candles.
When the spacing member is relatively thermoconductive, it may conveniently be made from metal and will function to stop the travel of the flame at a distance above the base region of the body of fuel, while still allowing the flame to burn and allowing some of the heat of the flame to be conducted by the second portion of the spacing member to warm the base region of the body of fuel, so creating a molten pool of fuel around, and in contact with, the base region of the wick. For this purpose, the second portion of the spacing member will be in thermal contact with the body of fuel. Furthermore, it will be understood that the spacing member must be configured or arranged so that the molten fuel can contact the base region of the wick during low burning. By so conducting heat to the base region of the body of fuel while maintaining the flame spaced above the base region of the body of fuel, the efficiency of melting of the base region of the body of fuel can be maintained or improved compared with known candles, while local overheating of any part of the base region of the body of fuel, or of any enclosure in contact with the base region of the body of fuel, can be restricted or prevented.
The spacing member thus serves to keep the flame away from direct contact with the base of the candle. Moreover, by selecting a desired degree of thermoconductivity of the spacing member, the flame will burn at its lower limit of travel for a greater or lesser length of time, depending on the amount of heat that is transferred to the base region of the fuel via the spacing member.
In the candle of the present invention, the risk of the low-burning candle flame igniting debris such as half-burned matches or pieces of wick which may have collected around the base of the wick is substantially reduced or eliminated.
The first portion of the spacing member is suitably a collar encircling (suitably closely) the wick. The second portion of the spacing member is suitably a downward extension of the collar of the first portion. The member preferably takes the form of a sleeve overlying the base region of the wick means. The sleeve may suitably have an internal diameter about 5% to about 200% more than the width of the wick. In the case of a typical wick width of about 2 mm to about 3 mm, the sleeve may suitably have an internal diameter of about 3 mm to about 8 mm, most suitably about 5 mm. The sleeve may suitably have a length of about 1 cm to 4 cm, most suitably about 2 cm, although this will vary (in ways which will be readily apparent to those of ordinary skill in this art) according to the overall dimensions of the candle and how low the end flame is desired to burn.
The wick is suitably constructed from conventional wick A material, for example cotton.
The fuel is suitably a conventional fuel such as wax or a hydrocarbon oil/polymer mix. Most preferably the fuel is solid at room temperature, but melts under the heat of the flame. A fragrance may suitably be incorporated, for example at levels of up to about 5 to 10% by weight. A suitable hydrocarbon oil/polymer mix consists of an approximately 9:1 by weight mixture of carnation oil and KRATON (TM) (Shell) triblock copolymer.
The body of fuel is suitably bounded by an enclosure which preferably comprises a receptacle (e.g. a bowl) having a base and a side wall. The enclosure is suitably of glass.
The candle according to the invention is manufactured by conventional methods, except that the spacing member is applied to overlie the wick means before the wick means is supported in the body of fuel. In the case of the preferred arrangement in which the fuel is solid at room temperature and the body of fuel is bounded by a glass bowl, for example, the base end of the wick is suitably first provided with a metal sustainer or collar flange which is crimped onto the base end of the wick and the flange part glued to the central region of the base of the bowl. The sleeve (or other member, if another configuration is to be used) is then fitted over the collar (or xe2x80x9cnosexe2x80x9d) of the sustainer to overlie the base region of the wick. There may be a gap at the lower end of the sleeve sufficient to allow molten fuel to enter the sleeve during low burning. The wick is then extended to be taut and the fuel is introduced as a molten liquid which then sets on cooling within the bowl and embeds the wick and spacing sleeve within its mass.
The invention prevents the flame from burning fully down. By placing the spacing member over the base of the wick, the flame burns down to the top of the spacing member but no further. Sufficient heat is transferred down the member to maintain a molten pool of fuel around the base of the wick, the pool being deeper the more thermoconductive the spacing m ember but still appreciable even with a relatively thermoinsulative (e.g. glass) spacing member. This molten fuel is then draw up the wick and ignited to feed the flame in conventional manner. Thus, the present invention can provide in effect a device which functions as a conventional candle until the flame reaches the top of the spacing member, and then optionally as a device similar to an oil burner. Depending on the configuration and thermoconductivity of the second portion of the spacing member, the device can potentially continue to operate until all of the fuel is consumed.